could underachieve
Regular verb: underachieve - underachieved- underachieved

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could underachieve
you could underachieve
he could underachieve
we could underachieve
you could underachieve
they could underachieve 	I could be underachieving
you could be underachieving
he could be underachieving
we could be underachieving
you could be underachieving
they could be underachieving	I could have underachieved
you could have underachieved
he could have underachieved
we could have underachieved
you could have underachieved
they could have underachieved	I could have been underachieving
you could have been underachieving
he could have been underachieving
we could have been underachieving
you could have been underachieving
they could have been underachieving	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't underachieve
you couldn't underachieve
he couldn't underachieve
we couldn't underachieve
you couldn't underachieve
they couldn't underachieve 	I couldn't be underachieving
you couldn't be underachieving
he couldn't be underachieving
we couldn't be underachieving
you couldn't be underachieving
they couldn't be underachieving	I couldn't have underachieved
you couldn't have underachieved
he couldn't have underachieved
we couldn't have underachieved
you couldn't have underachieved
they couldn't have underachieved	I couldn't have been underachieving
you couldn't have been underachieving
he couldn't have been underachieving
we couldn't have been underachieving
you couldn't have been underachieving
they couldn't have been underachieving	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I underachieve?
could you underachieve?
could he underachieve?
could we underachieve?
could you underachieve?
could they underachieve? 	could I be underachieving?
could you be underachieving?
could he be underachieving?
could we be underachieving?
could you be underachieving?
could they be underachieving? 	could I have underachieved?
could you have underachieved?
could he have underachieved?
could we have underachieved?
could you have underachieved?
could they have underachieved? 	could I have been underachieving?
could you have been underachieving?
could he have been underachieving?
could we have been underachieving?
could you have been underachieving?
could they have been underachieving? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I underachieve?
couldn't you underachieve?
couldn't he underachieve?
couldn't we underachieve?
couldn't you underachieve?
couldn't they underachieve? 	couldn't I be underachieving?
couldn't you be underachieving?
couldn't he be underachieving?
couldn't we be underachieving?
couldn't you be underachieving?
couldn't they be underachieving? 	couldn't I have underachieved?
couldn't you have underachieved?
couldn't he have underachieved?
couldn't we have underachieved?
couldn't you have underachieved?
couldn't they have underachieved? 	couldn't I have been underachieving?
couldn't you have been underachieving?
couldn't he have been underachieving?
couldn't we have been underachieving?
couldn't you have been underachieving?
couldn't they have been underachieving?